1. Field of the Invention
This invention relates to an impact printer and more particularly to a band type impact printer wherein the print band is contained within a replaceable cartridge.
2. Description of the Prior Art
One type of high speed printer apparatus involves the use of an endless type band or carrier having raised characters and timing marks on one side which is used for printing information onto a record medium. The type band is carried by a pair of pulleys, one of which is a drive pulley and the other of which is a driven, or idler, pulley. The drive pulley, during rotation, causes the print band to scan along a print line of a record medium. A plurality of print hammers are arranged at uniformly spaced print positions along the print line over which the type band travels. The actuation of any of the print hammers drives a record medium against the type band to thereby cause printing. The impacting of the record medium against the type faces by the print hammers occurs at predetermined times depending upon the time when a character desired to be printed is at a predetermined columnar location. This type of impact printer is a line printer which will print a line of information and then will cause the record medium to be advanced to a new line position, whereupon a new line of data will be printed, and the process is repeated.
The type band used in such a printer may consist of an endless metallic type band having raised characters along a first lineal circumferential portion of the band, and timing marks along another lineal circumferential portion of the band. One such printer is sold by Nortec Computer Devices Inc. as a Nortec 200 line printer, and now believed sold by IOMEC Corporation. Known prior art patents made of record in this application are U.S. Pat. Nos. 3,224,366, 3,362,325, 3,805,697. Also made of record are U.S. pat. application Ser. Nos. 453,224 and 453,473 filed Mar. 21, 1974, Jan F. Wenstrup, inventor, and assigned to the assignee of this invention.
The endless metallic type band has advantages over either the slug type mechanisms used in chain type printers, or the flexible bands which use flexible finger type elements. For example, the chain printer which uses slugs has type slugs which may be individually secured to a continuous carrier. The drawbacks of such slug type devices include frequent maintenance and replacement of parts and high manufacturing costs. On the other hand, endless metallic band printers have a number of desirable features. For example, different length bands or bands with different type fonts or character styles may be quickly installed on the printer. Such installation is facilitated by the present invention where the band is supported in a replaceable cartridge on a pair of pulleys. One of the pulleys is spring loaded and operates to hold the band on the pulleys under a predetermined amount of tension. In addition, the idler pulley is arranged to be adjustably spaced from the drive pulley so that different length bands may be employed.